Presently, there are two methods used for illuminating automotive instrument pointers. The first and oldest method involves frontlighting or floodlighting an opaque pointer, typically with an incandescent lightbulb. This method has several shortcomings, however. While it is desirous to design automotive instrument clusters to be as thin as possible to reduce the size of the automobile components and the amount of space required by those components, frontlighting or floodlighting requires depth in the cluster to accommodate the light source. Moreover, frontlighting or floodlighting can create shadows and glare, obscuring the pointer position.
The second method currently in use for illuminating automotive instrument pointers is a lightpipe pointer system. Incandescent lightpiping utilizes a remote incandescent bulb and an acrylic or polycarbonate lightpipe to concentrate the light on the hub of the pointer. The pointer is also made of acrylic or polycarbonate and is designed to direct or "lightpipe" the light from the hub to the viewer. This method has many of the same problems that exist with the frontlighting or floodlighting method of illumination. Moreover, the design, assembly and optimization of a lightpipe system is relatively time consuming and costly.
It has been previously proposed to backlight an instrument pointer with a large surface area thickfilm electroluminescent source, utilizing a light collecting film on the pointer to collect the emitted light. However, electroluminescent light is relatively dim and the pointer illumination is generally unsatisfactory.